1. Field of the Invention
The present invention relates to a retention device, and particularly to a retention device for retaining a heat sink module upon an LGA socket for dissipating heat.
2. Description of Related Art
IC packages having leads arranged in a land grid array (LGA) are well known as LGA packages. Connectors for removably mounting an LGA package on a PCB (Printed Circuit Board) are known as LGA sockets which are introduced, for example, in the internet website address: http://www.kns.com/prodserv/test-division/products/sockets/BGA-LGA.asp. LGA sockets, as described in U.S. Pat. Nos. 5,282,111, 5,485,351 and 5,702,256, each comprise a substantially flat insulative housing defining an array of passageways with electrical contacts received therein corresponding with the array of leads of the LGA package. Each contact has a pair of free ends oppositely projecting beyond external surfaces of the socket housing for respectively engaging with corresponding contact pads on a bottom surface of the LGA package and on a top surface of the PCB. To dissipate the heat generated by an IC chip incorporated in the LGA package, a heat sink device is commonly applied.
Different devices are disclosed by the prior art for clamping the LGA package, the LGA socket and the PCB together, thereby establishing an electrical connection between the contacts of the LGA socket and corresponding contact pads of the LGA package and the PCB. U.S. Pat. No. 4,906,194 discloses an LGA package assembly including an upper support clip, an LGA package, an LGA socket, a PCB, an insulator, and a lower support clip. The components of the LGA package assembly are fastened to each other by a plurality of threaded screw members sequentially extending through bores defined in each component. Such a manner of assembling is laborious and tedious. U.S. Pat. No. 5,847,928 discloses another LGA package assembly including a heat sink, an LGA package, an LGA socket and a PCB. The components are fastened together by a clip disposed on a bottom side of the PCB which has two upward extending arms inserted in aligned apertures of the PCB and the heat sink. One problem with this design is that the clip has the same profile no matter whether the heat sink is mounted upon the LGA package or not; this is disadvantageous in view of the inventory and shipment of the clip.
Hence, an improved retention device for an LGA connector assembly is required to overcome the disadvantages of the conventional retention device.
The object of the present invention is to provide a foldable retention device for an LGA connector assembly, wherein the retention device is foldable so that its profile can be reduced.
In order to achieve the object set forth, a retention device of the present invention comprises a main frame, a pair of front foldable plates, a pair of rear foldable plates, a spring clip and an actuating lever. The front and rear foldable plates are pivotably assembled to the main frame. The spring clip is pivotably assembled to the rear foldable plates, and comprises a downward extending pressing portion for pressing against the heat sink module and a receiving arm extending forwardly from a front end thereof. The actuating lever is pivotably assembled to the front foldable plates and rotated to lock the receiving arm. Therefore, the spring clip is pressed downwardly whereby the pressing portions press against a heat sink module and retain the heat sink module and an LGA package upon an LGA socket. While the heat sink module and the LGA package are removed from the LGA socket, the actuating lever and the spring clip maybe foldable to reduce occupied space.